WEST LAFAYETTE, Ind. - Researchers are developing a new class of "plasmonic metamaterials" as potential building blocks for advanced optical technologies, including ultrapowerful microscopes and computers, improved solar cells, and a possible invisibility cloak.
The new materials could make possible "nanophotonic" devices for numerous applications, said Alexandra Boltasseva, an assistant professor of electrical and computer engineering at Purdue University.
Unlike natural materials, metamaterials may possess an index of refraction less than one or less than zero. Refraction occurs as electromagnetic waves, including light, bend when passing from one material into another. It causes the bent-stick-in-water effect, which occurs when a stick placed in a glass of water appears crooked when viewed from the outside.
Being able to create materials with an index of refraction that's negative or between one and zero promises a range of potential breakthroughs in a new field called transformation optics. However, development of new technologies using metamaterials has been hindered by two major limitations: too much light is "lost," or absorbed by metals such as silver and gold contained in the metamaterials, and the materials need to be more precisely tuned so that they possess the proper index of refraction.
Now, researchers are proposing a new approach to overcome these obstacles. Findings will be detailed in an article appearing Friday (Jan. 21) in the journal Science. The article was written by Boltasseva and Harry Atwater, Howard Hughes Professor and a professor of applied physics and materials science at the California Institute of Technology.
The researchers are working to replace silver and gold in materials that are created using two options: making semiconductors more metallic by adding metal impurities to them; or adding non-metallic elements to metals, in effect making them less metallic. Examples of thes
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